Susan Collins, R-Maine, speaks with a reporters as she leaves the Senate Republicans' policy luncheon on Tuesday, June 28, 2016. (Photo By Bill Clark/CQ Roll Call)

Veteran Republicans are flabbergasted that the Obama administration has not once budged during four months of talks in demanding nearly $2 billion to fight the Zika virus outbreak, a posture that's helped stall emergency legislation.

The White House and Democrats who participated in the talks say the sum, first requested in February, reflected what senior federal health officials determined is needed to track the spread of the disease, develop vaccines and study links between Zika and birth defects, among other tasks.

House Majority Leader Kevin McCarthy said the Zika conference committee was close to compromising on an emergency spending proposal to combat the virus. (Tom Williams/CQ Roll Call file photo)

House Majority Leader Kevin McCarthy said Thursday the chamber may vote on a conference report addressing a response to the Zika virus outbreak next week if Senate and House negotiators produce a final package.

"I'm hopeful in my conversations with the conferees that they are close to finishing," McCarthy said.

An Aedes aegypti mosquito, seen through a microscope, which transmits the Zika virus. (Mario Tama/Getty Images)

As lawmakers leave for their Memorial Day break, a left-leaning think tank says more than 2 million pregnant women — and the children they are carrying — in the United States could be at risk of contracting the Zika virus.

The White House initiative would support research and diagnostics. (Photo By Al Drago/CQ Roll Call)

The Obama administration will ask Congress for $1.8 billion in emergency funding to combat the Zika virus -- a disease the president says is a cause for concern but not panic.

The White House announced the request to cover research and planning in the United States and abroad minutes after CBS aired an interview with President Barack Obama during which he said “there shouldn't be panic on this -- this is not something where people are going to die from.”